Preparations for the trip have taken more than six years, but Mr Lecomte has been targeting the challenge for much longer.

In 1998, he made the first known solo trans-Atlantic swim covering 6,400km (4,000 miles) in 73 days. When he finally reached dry land in France, his first words were "never again", but he was soon looking for a new challenge.

"It didn't take that long for me to change my mind," he told NPR. "Three, four months afterwards I was already thinking about my next adventure and doing something kind of the same."

Mr Lecomte's daily routine will remain virtually the same for the entire trip. He will swim for eight hours, jump onboard the support boat to eat and sleep, and then enter the water again.

To keep his energy levels high, he is aiming to consume 8,000 calories a day.

"I have a strict no sugar diet. Most of my calories will come from a high-fat diet and include a lot of freeze-dry full meals, rice, pasta and various soups," he posted during a Reddit interview earlier this month.

The support boat will be fitted with a GPS tracker and interested viewers will be able to track its progress on Mr Lecomte's website.